Method and apparatus for manufacturing bearing rings

ABSTRACT

Method and apparatus for forming ball bearing races from lengths of tubing. A mandrel is inserted into the interior of the tube. A die having a shape conforming to that of a ball bearing raceway is positioned about the exterior of the tube at approximately its midpoint. The opposite axial ends of the tube are then compressed by jaws to form shoulders on each axial end of the tube to form the raceway.

United States Patent Goguta [451 Aug. 22, 1972 [54] METHOD AND APPARATUSFOR 1,560,135 11/1925 Bell ......72/354 MANUFACTURING BEARING RINGS2,633,765 4/1953 Glasner ....72/354 [72] Inventor: Traian Gogum, Brasov,Romania 3,406,548 10/1968 WIICOX .,....72/370 X [73] Assignee: UzinaRulmentul, Brasov, Romania Primary ExaminerGranville Y. Custer, J r.

25 Att0rney-Spencer & Kaye [21] Appl. No.: 836,474 [57] ABSTRACT Methodand apparatus for forming ball bearing races Forelgn Application y Datay from lengths of tubing. A mandrel is inserted into the Jan. 16, 1969Romania 58780 interior of Ihembe- A die having a Shape conforming I tothat of a ball bearing raceway is positioned about 52 us. C1. ..72/354,72/370 the exterior of the tube at approximately its midpoint- [51] Int.Cl. ..B21d 22/06 The Opposite axial ends of th tu are then com- [58]Field of Search ..72/354, 370 pressed by jaws to form shoulders on eachaxial end of the tube to form the raceway. [56] References Cited 9 Claim3 Drawing Figures UNITED STATES PATENTS 412,389 10/1889 lsherwood..'...72/370 PATENTED M1822 m2 SHEI1UF !NVENTOR T'ralan Goal/fa. BY

41, ATTORNEY;

PATENTED M1822 m2 SHEET 3 HF NNNNNN OR METHOD AND APPARATUS FORMANUFACTURING BEARING RINGS BACKGROUND OF THE INVENTION The presentinvention relates to a method and apparatus for automatically producinginner race rings for rolling-contact bearings. The present methodproduces the race rings by cold working and uses stock tubing as theinput material.

It is well known in the art to form such race rings by plastic-workingtechniques; as, for example, by the hot rolling of rings whose initialcross section is rectangular. The requisite heating, however, produces adegradation of the rolled surface and subsequent machining requireslarge material allowances to be made.

It is also know to produce race rings by cold-rolling a workpiece withrollers having an appropriate profile and applied to the workpiece withgradually increasing pressure. The rollers, however, wear rapidlybecause of the high localized pressures involved.

Both the hot-rolling and cold-rolling processes referred to above havethe disadvantage that there are large local displacements of material inthe region in the bearing surface. These displacements cause slipping atthe grain boundaries with a resulting unfavorable effect on the fatigueproperties of the materi SUMMARY OF THE INVENTION The problems referredto above are overcome by a process according to the present invention inwhich the race is formed by a single, axial compression whichsimultaneously builds up the shoulders of the race groove on either sideof a die. This process causes a material to be gradually deformed aroundthe die without being displaced directly by a forming tool.

During the race forming process, the material gradually takes the formof the die.

' Lengths of stock tubing constructed from a suitable, known bearingsteel are used as the input material.

Rolling causes the granular structure of this type of steel to becomefibrous. In the method according to the present invention, the initialgranular structure improves due to the stretching and the thicknessreduction achieved when drawing the tube. This pronounced fibrousstructure provides a half-finished bearing ring with certain desirableproperties at the raceway due to a desirable orientation of fibers. Ithas been shown that in order to achieve bearings having a maximumservice life, the fibers of the material must be oriented so as not tobe cut by the surface of the raceway of the bearing ring.

Orientation of the fibers in the steel to conform with the contour ofthe surface of the raceway can be achieved by the process according tothe present invention.

The inner race of a rolling contact bearing normally fails first duringrunning of the bearing.

The method of the present invention includes the steps of inserting amandrel into the interior of a length of tube, placing a die about theexterior of the tube at approximately its midpoint, and compressing theopposite ends of the tube while the mandrel and die are so positioned toform shoulders on each axial end of the tube for retention of ballbearings. Before the above steps are carried out, the length of tube isprepared by the steps of placing the mandrel within the end of a tubularextensive length so that the mandrel end is positioned at a distancefrom the tube end equal to the length of tube required to shape one ballbearing raceway, and cutting the tube with the mandrel therein at thepoint to which the end of the mandrel extends.

Apparatus for carrying out the method of the present invention is alsoprovided. This apparatus has a support structure, sleeve means having anaxial end mounted on the support structure for holding a tube to beprocessed within it with one end of the tube extending past the axialend, a mandrel having an axial end and arranged to be inserted withinthe tube, means mounting the mandrel on the support to move the mandrelinto the tube with the axial end of the mandrel positioned and alignedwith the end of the sleeve, a cutting tool having a cutting edge forcutting the portion of the tube projecting beyond the axial end of thesleeve means, means mounting the cutting tool for movement of thecutting edge in engagement with the axial end of the sleeve to therebycut the portion of the tube projecting beyond the axial end of thesleeve from the remainder of the tube, a die having a shapecorresponding to the exterior of the ball bearing raceway to be pressed,means mounting the die on the support structure for movement about theexterior of a cut section of the tube, a pair of jaws for pressingopposite axial ends of the cut section of the tube, and meansmountingthe jaw on the support structure for movement to axially compress theopposite tube ends to thereby form shoulders at each axial end of thetube to form a groove in the central region of the tube and thereby formbearing raceway.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic showing, partlyin cross section, of a first operating position of apparatus forperforming the method according to the present invention.

FIG. 2 is a'schematic showing similar to FIG. 1 with the apparatus in asecond operating position.

FIG. 3 is a partly schematic top plan view of the die for forming thebearing ring, together with the die actuating device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The pressing apparatusaccording to the present invention is arranged on a support structure S,as can be seen in FIGS. 1 and 2 of the drawings. The partialtopright-to-bottom-left hatching indicates the various segmentsof thissupport structure S.

Pressing jaws A and B are mounted on the structure S in opposedrelationship for movement toward and away from one another. The jaws Aand B are represented in FIGS. 1 and 2 by the partialtop-left-tobottom-right hatching.

The apparatus is actuated by a suitable, known motor M. Motor M rotatesa pair of cam shafts 1 and 2. Cams C and C are mounted on cam shaft 1and earns C through C are mounted on cam shaft 2. Rotary motion istransferred from cam shaft 1 to cam shaft 2 by means of a pair ofsuitable, known bevel gears.

The jaws A and B are mechanically actuated that is, hydraulically orpneumatically through piston and aball cylinder arrangements 3 and 4.Each piston and cylinder arrangement 3 and 4 contains a respectivepiston 5. Each piston 5 has a piston rod connected to respective,opposed pivot points of a four-bar linkage 6 in the form of aparallelogram. This linkage 6 has pivot points 7 and 8 in addition tothose connected to pistons 5. Pivot point 7 is connected to jaw A, andpivot point 8 is connected to a rod 8. Rod 8' is in turn connected tobars 8" which are fixed to jaw B. A spacer or intermediate member 13 isprovided and arranged to slide between an area 9 and an area 9. Theseareas are configured in any conventional manner to accommodate thespacer l3 and the cut section of tube 0 as they are translatedtherebetween in still another conventional manner to be describedhereinafter.

The purpose of the apparatus according to the present invention is tointermittently feed an extensive length of tubing, or pipe, a distancefrom an end of the tube which is equal to the length of a tube sectionrequired to shape one ball bearing raceway, to cut the tube, to transferthe blank or cut tube section to a position between jaws A and B, toplace a die 21, 22 having a cross section corresponding to the desiredfinal shape toridial in the case of ball bearing races around the cuttube section, to axially compress the cut tube section, to apredetermined length L (FIG. 2), to engage the bore of the sheered pipeat the cut end thereof, to retract the jaws A and B, to separate thecomponent segments 21 and 22 of the die, to remove a pin on which thepressing was obtained, and to reject 14 arranged to be insertedwithinthe tube 0 so that the previously pressed bearing ring'and initiate anew cycle. As mentioned above, the cams C to C mounted on cam shafts land 2 are provided for this purpose. These cams act in conjunction withsuitable, known actuators 18, 23, and 27 through 30 to actuate thevarious elements of the press in'their proper sequence. The ac- Ituators are supplied from a pressure source through a manifoldarrangement shown schematically at M.

All of the members which are directly attached to the body of the press,as well as those arranged adjacent the cams, are directly actuated. Themost remote parts, namely those mounted for movement with the jaws A andB, are remotely controlled through suitable linkages from the manifoldand actuators to piston and cylinder arrangements to be describedhereinafter. A rod provided with a mandrel 1 1 on its end is introducedinto a tube, or pipe, 0 of extensive length to prevent flatteningthereof. Tube 0 is inserted into a known feeding system X. This feedingsystem X is hydraulically or pneumatically actuated. Mandrel 11 iscoupled to a dismountable, moving elastic link-coupling Y, which is inturn attached to the supporting structure forming the press body.

A special sleeve 12 is arranged about the end of the tube 0. This sleeve12 is integral with the supporting structure S.

Spacer 13 in the position shown in FIG. 1 acts as a stop for tube 0 andthereby determines the length of tube 0 to be cut.

A pin or mandrel 14 is inserted into the end of tube 0 to cooperate withmandrel l 1 and prevent the deformation of the tube 0 in the shear planeduring the cutting step. Pin 14 along with spacer 13 functions totransfer the cut tube section, or blank, into position to have a racewaypressed thereinto. The pin 14 has an axial end the end 14 is positionedat a distance from the tube end equal to the length of tube required toshape one ball bearing raceway. An elastic latch 15 is provided to holdpin 14 in position. A cutting-off tool 16 shears the tube 0 by aleft-to-right movement in FIGS. 1 and 2. The movement of tool 16, whichdefines a bore for receiving a pin 17 which is similar to pin 14, is controlled by cam C,. This cam pushes tool 16 with great force from theposition shown in FIG. 1 to the position shown in FIG. 2, thusperforming the shearing of tube 0. The shape of the cutting edge of thetool 16 can be any desired shape suited for the purpose which is withinthe expertise of the ordinarily skilled artisan. At the end of thestroke of the cutting-off tool 16 (FIG. 2) the axis of pin 17 is alignedwith the axis of sleeve 12. In the following description ofthepositioning of the actuators 18, 23, and 27 through 30 by cams C throughC respectively, the letter p is always used to designate the incomingmedium under pressure. This pressure p is derived from a known sourcewhich is not shown in the drawings.

Cam C positions actuator 18 to direct pressure p to the piston andcylinder arrangements 19 and 20 (FIG. 3). These piston and cylinderarrangements 19 and 20 open and close the die 21, 22 by manipulatingrespective ones of the die-segments 21 and 22. The die segments 21 and22 define the groove of the raceway to be formed in the cut tubesection. Piston and cylinder arrangements 1 9 and 20 are actuated bymeans of pressure from outlets a and b of actuator 18 beingalternatively' directed to the corresponding openings in the cylindersof arrangements 19 and 20. That is, outlets a and b are connected tocorresponding openings a and b respectively.

The cut tube section is now transferred to a position between jaws A andB of the press. For this purpose, cam C positions actuator 23 which isprovided with channels c and d. Channels 0 and d are connected torespective openings, which are designated c and d, in the cylinder of apiston and cylinder arrangement 24. Arrangement 24 is arranged topositively displace spacer 13, along with pin 14 and the cut tubesection. For this purpose a connection 24 is made between the spacer 13and the rod 24" of the arrangement 24. As is clearly evident from FIGS.1 and 2, the connection 24' is preferably of a sliding type whichpermits the spacer 13 to move with jaw B during compression of tube 0.

Simultaneously with the cutting of tube or pipe 0, cam C positionsactuator 23 to direct pressure into channel d. This pressure moves thepiston of arrangement 24 from the position shown in FIG. 1 to theposition shown in FIG. 2, and positively displaces spacer 13 and pin 14to move the cut tube section into the position shown in FIG. 2. Now thecompressing step can begin.

When spacer 13 and pin 14 are moved to the position shown in FIG. 2 ofthe drawings, the free end of pin 14 comes into engagement with and iscoupled to a retaining section of member 26. Simultaneously, themovement of tool 16 and pin 17 into the position shown in FIG. 2 movespin 17 into a position to be coupled to the retaining section of amember 25.

Members 25 and 26 are mounted for reciprocating movement along theirvertical axes in FIGS. 1 and 2,

and are actuated by cams C and C respectively. Cam C acts directly onmember 25, while cam C positions an actuator 28 which actuates a pistonand cylinder arrangement 29 to reciprocate member 26.

Once the elements are in the positions shown in FIG. 2 of the drawings,cam C positions actuator 18 to direct pressure p through channel a andopening a to actuate arrangements 19 and 20 and close and lock the diesegments 21 and 22. Cam C now positions actuator 27 to direct pressure pthrough channel e to openings e of cylinders 3 and 4. The pistons 5 ofcylinders 3 and 4 move toward one another and, thus, cause jaws A and Bto move toward one another. As jaws A and B move toward one another, thecut tube section, or blank, is upset to the required length L.

Cam C then positions manifold 18 to direct pressure p through channel band opening b to unlock and open die segments 21 and 22.

Next, Cam positions actuator 27 to direct pressure p through channel fto opening f and moves jaws A and B away from one another into theirposition shown in FIG. 1.

When this is accomplished, cam C moves member 25 from its position shownin FIG. 1 into its position shown in FIG. 2 and inserts pin 17 into thetube 0. Thus, possible irregularities in the cross section of tube atthe sheared section thereof are dressed. Then cam C returns member 25 toits FIG. 1 position and withdraws pin 17.

Now cam C positions actuator 28 to direct pressure p to arrangement 29such that member 26 is moved upwardly as seen in FIGS. 1 and 2, and pin14 is removed from the pressed bearing ring. The bearing ring then dropsdown off the press. A further rotation of cam C replaces pin 14 in itsinitial position with respect to spacer 13.

After the pin 14 has been returned to its initial position, cams C and Cact to return spacer l3 and tool 16, respectively, to their initialposition shown in FIG. 1. Cam C positions actuator 30 to position systemX through channels g and h. System X then moves tube 0 a length L in theupward direction of FIG. 1, and the process set out above is thenrepeated. Cam shafts l and 2 are arranged such that one cycle iscompleted within a 360 revolution of these cam shafts 1 and 2, so thatfurther rotation of the cam shafts 1 and 2 will start a new cycle.

When compared with the known processes, the new cold working techniqueaccording to the present invention demonstrates the followingadvantages:

a perfect material structure is obtained in that the direction of thefibers is parallel to the groove of the pressed bearing rings;

rolling-contact bearing rings are produced which require low machiningallowances; that is, the material and labor consumption is very low;

forming by cold-pressing results in lower tool wear and lessthermoenergy consumption than a hot working technique would require.

deformation is achieved with only compression stresses being produced inthe workpiece and the tool, and occurs little by little throughout thematerial. As a result, slip and faults at the grain boundaries of thematerial are avoided;

special extra machines to precut the material are not required;

bearing rings are obtained by the method according to' the presentinvention efficiently and without the material waste which would occurif the rings were turned.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes andadaptations, and the same are intended to be comprehended within themeaning and range of equivalents of the appended claims.

Iclaim:

l. A method of manufacturing ball bearing races, comprising, incombination, and in any desired order:

a. placing a mandrel within the interior of a tube section, placing adie about the exterior of the tube section at approximately itsmidpoint, and

. compressing the opposite ends of the tube section while said mandreland die are so positioned to form shoulders on each axial end of thetube section for retention of ball bearings.

. The method of claim 1 including the steps of:

. placing said mandrel within the end of a tube of extensive length sothat the mandrel end is positioned at a distance from a tube end equalto the length of the tube section required to shape one ball bearingraceway.

b. cutting the tube with the mandrel therein at the point to which theend of said mandrel extends c. thereafter performing said die placingand said compressing steps. while the mandrel remains within said cuttube section.

3. The method of claim 2 including the step of reshaping any of theportions of the interior of the tube which are deformed during saidcutting operation by inserting a pin of larger dimensions than expecteddeformations within the tube bore, and moving said pin axially past saiddeformed regions.

4. The method of claim 1 including performing said die placing step bysimultaneously moving segments of a die together on radially oppositeouter surfaces of the tube section and bringing the edges of saidsegments into engagement with each other to thereby form a complete diesurrounding the tube section.

5. Apparatus for the manufacturing of ball bearing races from tubes,comprising, in combination:

a. support structure,

b. sleeve means having an axial end mounted on said support structurefor holding a tube to be processed within it with one end of the tubeextending past said axial end, mandrel means for inserting within thetube, said mandrel means having an axial end,

. means mounting said mandrel means on said support structure to movesaid mandrel means into the tube with said axial end of the mandrelmeans positioned in alignment with the end of said sleeve means,

. cutting tool means having a cutting edge for cutting the portion ofthe tube projecting beyond said axial end of said sleeve means,

. means mounting said cutting tool for movement of said cutting edge inengagement with said axial end of said sleeve means to thereby cut theportion of the tube projecting beyond said axial end of the sleeve meansfrom the remainder of said tube,

die means having a shape corresponding to the exterior of a ball bearingraceway to be pressed,

h. means mounting said die means on said support structure for movementabout the exterior of a cut section of the tube,

i. a pair of jaw means for pressing opposite axial ends of said cutsection of the tube, and

j. means mounting said jaw means on said support structure for movementto axially compress the opposite tube ends to thereby form shoulders ateach axial end of the tube bordering a groove in the central region ofthe tube and thereby form a ball bearing raceway.

6. The combination of claim in which said means mounting said jaws movethe jaws simultaneously and at the same speed during said axiallycompression movement,

7. The combination defined in claim 6 wherein said jaw moving meansinclude two pressure cylinder means mounted on said support structureand a parallelogram linkage system connecting the two cylinder meanswith the two jaw means to provide said simultaneous movement.

8. The combination defined in claim 5 including pin means havingexterior dimensions larger than the expected dimensions of portions ofthe tube which are distorted during said cutting action, and meansmounting said pin means for axial movement within the interior of one ofsaid tubes after cutting and past any distorted regions to therebyreshape regions of the tube distorted by cutting.

9. The combination of claim 5 including:

a. a bore within said cutting tool and means mounting said pin withinsaid bore and said cutting tool to bring said bore in co-axial alignmentwith the end of the bore of uncut portions of the tube,

b. a spacer member, means mounting said mandrel within said spacermember for movement from a first position in which said bore is coaxialwith said uncut tube to a second position in which said bore is co-axialwith a bore in one of said jaws, said means further mounting saidmandrel for movement of a portion thereof into said jaw bore while meanscarried by said support structure for moving said mandrel out of saidjaw bore and the cut tube section after said ball bearing race isformed,

d. means carried by said support structure for moving said pin out ofsaid uncut portion of the tube after said reshaping action is completed,and wherein said jaw moving means includes two pressure cylinders and aparallelogram linkage system connecting the two cylinders with the twojaws to provide simultaneous movement of said jaws at the same speedduring said axial compressure movement, and

.said die is formed of a plurality of segments and I means on saidsupport structure for moving said segments together to form a completedie surrounding the tube.

1. A method of manufacturing ball bearing races, comprising, incombination, and in any desired order: a. placing a mandrel within theinterior of a tube section, b. placing a die about the exterior of thetube section at approximately its midpoint, and c. compressing theopposite ends of the tube section while said mandrel and die are sopositioned to form shoulders on each axial end of the tube section forretention of ball bearings.
 2. The method of claim 1 including the stepsof: a. placing said mandrel within the end of a tube of extensive lengthso that the mandrel end is positioned at a distance from a tube endequal to the length of the tube section required to shape one ballbearing raceway. b. cutting the tube with the mandrel therein at thepoint to which the end of said mandrel extends c. thereafter performingsaid die placing and said compressing steps while the mandrel remainswithin said cut tube section.
 3. The method of claim 2 including thestep of reshaping any of the portions of the interior of the tube whichare deformed during said cutting operation by inserting a pin of largerdimensions than expected deformations within the tube bore, and movingsaid pin axially past said deformed regions.
 4. The method of claim 1including performing said die placing step by simultaneously movingsegments of a die together on radially opposite outer surfaces of thetube section and bringing the edges of said segments into engagementwith each other to thereby form a complete die surrounding the tubesection.
 5. Apparatus for the manufacturing of ball bearing races fromtubes, comprising, in combination: a. a support structure, b. sleevemeans having an axial end mounted on said support structure for holdinga tube to be processed within it with one end of the tube extending pastsaid axiaL end, c. mandrel means for inserting within the tube, saidmandrel means having an axial end, d. means mounting said mandrel meanson said support structure to move said mandrel means into the tube withsaid axial end of the mandrel means positioned in alignment with the endof said sleeve means, e. cutting tool means having a cutting edge forcutting the portion of the tube projecting beyond said axial end of saidsleeve means, f. means mounting said cutting tool for movement of saidcutting edge in engagement with said axial end of said sleeve means tothereby cut the portion of the tube projecting beyond said axial end ofthe sleeve means from the remainder of said tube, g. die means having ashape corresponding to the exterior of a ball bearing raceway to bepressed, h. means mounting said die means on said support structure formovement about the exterior of a cut section of the tube, i. a pair ofjaw means for pressing opposite axial ends of said cut section of thetube, and j. means mounting said jaw means on said support structure formovement to axially compress the opposite tube ends to thereby formshoulders at each axial end of the tube bordering a groove in thecentral region of the tube and thereby form a ball bearing raceway. 6.The combination of claim 5 in which said means mounting said jaws movethe jaws simultaneously and at the same speed during said axiallycompression movement.
 7. The combination defined in claim 6 wherein saidjaw moving means include two pressure cylinder means mounted on saidsupport structure and a parallelogram linkage system connecting the twocylinder means with the two jaw means to provide said simultaneousmovement.
 8. The combination defined in claim 5 including pin meanshaving exterior dimensions larger than the expected dimensions ofportions of the tube which are distorted during said cutting action, andmeans mounting said pin means for axial movement within the interior ofone of said tubes after cutting and past any distorted regions tothereby reshape regions of the tube distorted by cutting.
 9. Thecombination of claim 5 including: a. a bore within said cutting tool andmeans mounting said pin within said bore and said cutting tool to bringsaid bore in co-axial alignment with the end of the bore of uncutportions of the tube, b. a spacer member, means mounting said mandrelwithin said spacer member for movement from a first position in whichsaid bore is coaxial with said uncut tube to a second position in whichsaid bore is co-axial with a bore in one of said jaws, said meansfurther mounting said mandrel for movement of a portion thereof intosaid jaw bore while the remaining portion remains within said spacerbore and the cut tube bore whereby during movement from said firstposition to said second position the mandrel moves said cut section ofsaid tube to said jaw means said mandrel then moves into said jaw boreand said spacer engages one of said axial ends of said jaw and is itselfengaged by the other of the said jaws to transmit compressing forcesfrom said other jaw to said tube section, c. means carried by saidsupport structure for moving said mandrel out of said jaw bore and thecut tube section after said ball bearing race is formed, d. meanscarried by said support structure for moving said pin out of said uncutportion of the tube after said reshaping action is completed, andwherein e. said jaw moving means includes two pressure cylinders and aparallelogram linkage system connecting the two cylinders with the twojaws to provide simultaneous movement of said jaws at the same speedduring said axial compressure movement, and f. said die is formed of aplurality of segments and means on said support structure for movingsaid segments together to form a complete die surrounding the tube.